Sunday, June 07, 2009

Varying the data to the test

The same test's need to be run, but the data we pass to it must be varied.
In addition further tests may need to change their behavior depending on the data. E.g. A user registering may provide different data , and subsequent screens may change depending on what the user has entered or may be skipped altogether. A common scenario is when a user registers to a site has various options he can choose from , and we need to test the behavior of the site for different combinations

JMeter provides multiple ways to vary the data
a. Use of User Parameters [1]
b. Use of Variables [2]
c. CSV Data Set Config [3]
The solution we will use is Option c.

The advantage of using CSV Data Set Config is that the data is externalised from the test , and can be updated by any user including a non technical business person. By making the assertion a part of the data, users can add more tests without needing the test itself to be modified. The other advantage of a CSV Data Set Config over a User Parameters pre processor is that the number of items that will be tested is fixed independent of the number of threads you will run (assuming you write the test in that fashion) OR can be made dependent on the number of threads. User Parameters is more closely tied to the number of threads.
e.g. If you wanted to create 10 distinct users , you'd only have 10 rows in your CSV data set config and you could use 1 to 10 threads. But if you needed to do this with User Parameters you'd probably need to specify exactly 10 threads.

So the solution takes the form of
a. Create a CSV Data Set Config element and point it to the CSV files.
b. Create your tests to use this data
If you want as many tests as you have rows in your CSV file, then you can either end the thread or use a Loop Controller an check for the special value ''<EOF>"


[1] User Parameters
[2] Variables
[3] CSV Data Set Config

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